On Thu, 24 Oct 2002, Paula J. Graffam wrote:
> Listers,
Howdy...
> Anyone care to give an opinion about Triple Weber carbs vs. ZS ? Is
> anyone driving with Webers and are you pleased or not?
Hmmmm. One of my hot-button topics. Sure, I'll provide opinions.
First off, this conversion is not a simple bolt-on. You need to tune the
carbs to the way you use the car. If you cruise at 60 on the freeway, you
want one setting, if you drive around with your right foot mashed to the
firewall, then you need a completely different setup.
To tune the things up properly, you need access to both a dyno and a
person that knows Webers. If you don't have access to either, then the
process of setting up DCOE 40's can be very frustrating. You should also
have accees (or own) one of the major Weber books, listed in order of
content: Passini, Braden, Haynes (there are at least two others that I
own). Passini is next to impossible to read, but the good stuff is all
there. The others are easier to read but lacking in good useful content
(other than pictures).
Now - to tune them, your motor must be in _perfect_ tune. This means good
compression, cam okay, ignition PERFECT... then you can tune. If you
don't follow this simple rule, you will spend incalculable hours chasing
your tail trying to get the carbs dialed in.
Now here's the kicker. Each DCOE40 has two of everything, so when you
make a change, you need to buy _SIX_ of whatever you want to try. As you
can imagine, this adds up pretty fast. This is the principle reason that
you need to deal with a Weber expert when you embark on this journey. An
expert will have boxes of jets, air correctors, idle jets, emulsion tubes
etc. that they can try for your car... once you get it right, you just pay
for what you use. If you do this yourself (buying a few jets at a time),
you will be like most of us with Weber DCOE 40's on the TR6 and have a box
of jets left over for "tuning" later... and the guys that sell the brass
bits won't take 'em back (for obvious reasons). $200 on a dyno can save
you a lot more than $200 worth of brass.
The general point of Webers is that they are almost infinitely adjustable.
This is also a drawback, because there might 10 ways you can set 'em up
for a TR6 and all of them are different in thier own ways - and trying to
mix and match won't work so theres infinity minus 10 ways you can get 'em
wrong!
That having been said, I've been a Weber user for about 6 seasons. I came
up with two settings for my street car (that I also raced for two of the 5
years) that worked pretty well. I could get 26 MPG on the highway at 70
MPH. I drove that setup for close to 20K miles (9k miles in one year!).
The thing was that once I got set up for the street, the car was a dog
when I raced. So, I made another setup of emulsion tubes/air
correctors/main jets to stick in when I raced. This was all well and good
'till I broke one of the tubes the night before a race... then I started
the "spares" collection.
Bottom line - Webers are awesome, but tricky to set up. Once they are
setup correctly, there is very little maintenance other than making sure
that the screws are tight and things aren't leaking too much. (By the way,
the Italians have nothing on the British when it comes to leaky and
finicky!) Synching them is fairly easy with a UniSyn, and they do seem to
stay in synch unless you pull the linkages off all the time...
The second question was a comparison between Z.S's and Webers. For all out
air flow capability, the Webers have it over the Z.S's merely due to the
cross section of the throats. BUT, you need to tweak a TR6 a lot to get
the flow up to enough to have the carb be the limiting factor in the
system... so, the Z.S's are pretty capable. For real data on this, look at
the Comp Prep Manual graphs of the power curves. Substitute Weber for PI
and you should get an idea of the potential. Note that the Weber will be a
bit less efficient than a real fuel injection system, but not a whole lot
less efficient.
And, as I've said many times on the Triumphs list - Webers do have that
certain "cachet"... argh, argH ARGH. But the purchase cost is only the
entry fee. You NEED electronic ignition or a really good points setup (I
use a Mallory dual point in the race car with an MSD Blaster 2 coil (no
spark box) and I can run .040 gaps, so that would be a "good spark". You
NEED an electric fuel pump (WOT on a TR6 with Webers can use a lot of
fuel, I get about 3 MPG autocrossing!) And you need to allocate at least
$200 for dyno time and another unknown quantity for dialing the carbs in.
> Al Graffam 74TR6 CT.
regards,
rml
74 TR6 - Street
73 TR6 - Race
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